1. Technical Field
The present invention relates to a discharge lamp lighting device, a projector, and a discharge lamp lighting method.
2. Related Art
As a light source of a projector, there is used a discharge lamp such as a high-pressure mercury lamp or a metal halide lamp.
In order to prevent the damage of the electrodes of the discharge lamp, there is disclosed in JP-A-2009-9885 (Document 1) a lighting control device, which applies high-voltage pulses for causing dielectric breakdown between the electrodes of the discharge lamp, and then applies symmetrical alternating current between the electrodes.
As described also in Document 1, the arc discharge occurs after passing through the period of the glow discharge immediately after starting the lighting operation of the discharge lamp. During the glow discharge, the blackening phenomenon that the electrode material (e.g., tungsten) is deposited on a sealed body of the discharge lamp due to sputtering becomes easy to occur. If the blackening phenomenon occurs, the blackened portion absorbs the light to thereby increase the temperature of the discharge lamp, and glass or the like used for the sealed body is melted and then resolidified to thereby cause a devitrification phenomenon to occur. If the devitrification phenomenon occurs, the illuminance of the discharge lamp is degraded, or the sealed body becomes easy to be damaged, and therefore, it is important to prevent the blackening phenomenon from occurring in order to elongate the product life of the discharge lamp.